[Differential] D7185: Add virtio-console support to bhyve

[Peter Grehan]

Hi Jakub,

> The purpose of virtio-console is to create arbitrary bidirectional,
> host-to-guest communication channels that bypass guest's network
> stack (don't require working networking in the guest).

  Could virtio-vsock be a better solution for this ? Docker's hyperkit 
has an implementation, though it appears Linux guest support is very recent.
    https://github.com/docker/hyperkit/blob/af-vsock/src/pci_virtio_sock.c

> But even for
> using it as the system console, it's a bit better than emulated
> serial port, because the protocol supports passing console resize
> events from host to guest.

  It makes for an excellent serial port since it uses descriptor rings 
for data transfer, but the lack of a simple polled-mode operation 
(unless the emergency support is used) isn't the best for a system console.

later,

Peter.